Semiconductor light-emitting elements emit light from a light-emitting layer that is formed by p-type and n-type semiconductors having an active layer therebetween. Thus, light is emitted in all directions. However, in many applications using the semiconductor light-emitting elements as light sources, it is often desired that light be emitted in one direction. In such cases, light that travels in directions different from the radiation direction is wasted. In order to efficiently use light, it is preferable to reflect such light toward a light-emitting surface of the semiconductor light-emitting element.
As a solution to this problem, semiconductor light-emitting elements have been proposed in which the side surfaces of the semiconductor light-emitting element are tilted so that light is directed toward a light-emitting surface. For example, Patent Document 1 shows a semiconductor light-emitting element having tilted side surfaces on an electrode, and having a reflective layer on each of the tilted surfaces. In this semiconductor light-emitting element, electrodes are provided on both sides of a light-emitting layer. In order to increase light extraction efficiency from the light-emitting layer, a sapphire substrate used to form the light-emitting layer is later delaminated with laser light.
Patent Document 2 shows a semiconductor light-emitting element in which an electrode is formed on one surface of a transparent substrate, and the bottom surface opposite to a light-emitting surface has slopes so that light generated by a light-emitting layer is not incident on the electrode.
These are examples in which a reflective layer is made of a metal thin film such as a vapor deposition film. However, since forming the reflective layer by the metal thin film or the like requires processing in a vacuum chamber, these examples are not necessarily suitable for mass production.
Another approach is to direct light from the side surfaces of a light-emitting device including a lead frame and a sealant, toward a light-emitting surface, instead of providing a reflective layer on the side surfaces of a semiconductor light-emitting element itself As such an approach, Patent Document 3 proposes a semiconductor light-emitting device having a reflective frame on the side surfaces of a sealing resin that seals a semiconductor light-emitting element.
FIG. 14 is a cross-sectional view of this semiconductor light-emitting device. A semiconductor light-emitting element 92 formed on a lead frame 90 is electrically coupled to another lead frame 96 by bonding 94. The entire semiconductor light-emitting element 92 is sealed with a resin 98, and a reflective frame 100 is provided on the side surfaces of the resin 98. With this configuration, light is reflected by the side surfaces, and is extracted from a light-emitting surface of the semiconductor light-emitting device.